Escapement drive



July 30, 1963 R. c. GEIGER ESCAPEMENT DRIVE Filed Feb. l0, 1961 IN VENTOR.

RUSSELL C. GEIGER BY i [ATTORNEYS United States Patent O M 3,099,164ESCAPEMENT DRIVE Russeli C. Geiger, Troy, Ohio, assignor to The HobartManufacturing Company, Troy, Ohio, a corporation of Gixio Filed Feb. 10,1961, Ser. N 88,322 4 Claims. (Cl. 74-125) This invention relates to anintermittent drive, and particularly to such a drive as applied totiming apparatus used to control the sequence of operations in thefunctions cycle of a dishwashing machine or similar machines.

4Intermittent drive mechanisms broadly have utility in the conversion-of input, usually continuous, rotary motion into intermittent motion,either rotary or linear, of predetermined increments. One particular useof mechanism of this type is in the driving of multiple cams whichcontrol the opening )and closing of switch contacts to form incombination a programming or sequencing timer construction. Byconnecting the intermittent output to the timer cams, they can be'advanced in a step by step fashion which will promote rapid opening andclosing of the switch contacts, ygiving an abrupt operation of thevarious switching elements of the timer and thus minimizing `arcing andeventual :destruction of the contacts, as well as giving a precisecontrol over the several differently timed functions 4of the machinebeing controlled by the timer. At the same time, the drive to themechanism can be from a continuously rotating small electric motor.

Of course, it is desirable to provide a timer construction which isdurable and has a relatively lon-g life, since in dishwashing machinesand the like it is preferable to avoid las much maintenance work on thetimer as possible. On the other hand, the driving parts of the mechanismoperate continuously through each running cycle of the machine, and thusthese parts are subjected to extensive use.

particularly the wear in the parts due to friction, in the timer driveas much as possible, and the primary object of this invention is toprovide a novel intermittent and drive, particularly adapted for thedriving of timer mechanisms, in which the friction between moving partsof the mechanism is minimized to a considerable extent, and friction-alwear is correspondingly reduced.

Another object of this invention is to provide an intermittent drive inwhich the intermittent driving motion imparted to a ratchet Wheel by adriving dog is carefully controlled to maintain the acceleration anddeceleration of the driving dog during its actuating motion withincontrolled limits, thus minimizing the tendency of the dog to throw theratchet Wheel Ibeyond the normal step of its intermittent motion, andproviding a step by step output which is more clearly constant as tochanges in rotational velocity. f

An additional object of this invention is to provide novel intermittentdrive in which a pivotal driving arm is provided having a cam surfaceengaged in sequence with a plurality of rollers driven in planetaryfashion, and in which such oam surface is contoured to maintain apredeterm-ined contact between a roller and the arm during rising anddescending motion of the arm to produce a driving action of the drivingdog of the drive mechanism.

Another object of this invention is to provide such a Accordingly, it isimportant to reduce the friction, and

A 3,099,164 Patented July 30, 1963 lCe timer drive which, in combinationwith the timer controls, functions to stop the drive mechanism at aposition where the lock-in mechanism Iof the driving dog is not fullyapplied, and the timer ratchet Wheel is therefore maintained relativelyfree lfor subsequent manual movement to start a new cycle of timeroperation.

Other objects and advantages of the invention will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

In the drawings- FIG. 1 is a plan view, with some parts broken away, 4ofan intermittent drive in accordance with the invention;

FIG. 2 is a sectional view, taken on line 2 2 of FIG. 1, and `showing inaddition, in dotted lines, a portion of a timing apparatus which may beIdriven yby the intermittent drive;

FIG. 3 is an enlarged det-ail section showing the beveledgedconstruction of one of the drive rollers;

FIG. 4 is a View of 1a preferred form of cam and roller `drive inaccordance with the invention, showing the movement of the drive cam armin `full and dotted lines, respectively;

FIG. 5 is an enlarged det-ail view illustrating the relationship of adrive roller :and a ramp portion of the cam by means of which thereciprocating arm is controlled during its advancing or descendingmotion; and

FIG. -6 is a somewhat schematic View of the timer mechanism,illustrating particularly the relationship of the parts at the end ofthe cycle, where the timer drive motor is stopped.

Referring to the drawings, which illustrate a preferred embodiment ofthe present invention, the drive is illustrated in combination with atimer device such as disclosed in United States Patent No. 2,916,923,issued December 15, 1959. The essential parts of such timer mechanisminclude a drive motor 10, shown schematically, which is connected torotate a pinion 12, preferably continuously, although the drive could beintermittent if desired. This pinion in turn is meshed with a reductiongear unit including a relatively large gear l13 and a smaller drive gear14 -both of which are carried on, and iixed, to a rcountershaft 15. Thesmaller gear 14 is in mesh with the maingear 18, and this main gear ismounted for free rotation about the main supporting shaft 20 of themechanism.

The gear 18 cooperates with a wheel 22 to form a support and drive for aplurality of planetary drive rollers 2S. in the embodiment shown, thereare three such rollers located symmetrically, apart, and thus capable ofproducing a driving stroke for every one-third revolution of the maingear 18, as will be described. The rollers 25 include a hub 27 whichextends into holes `28 formed in the gear 018 and the wheel 22,respectively. These parts are maintained in properly spaced relation topermit free rotaton of rollers 25 by a center spider 30'. The edges ofrollers 25 are preferably beveled (FIG. 3) to minimize frictionalresistance to rotation of any roller in its mounting.

The spider construction preferably includes a plurality of outwardlyextending ears 32 provided with holes 33, and the gear 18 and `Wheel 22are dirnpled or otherwise suitably deformed, as shown l.generally at 34in lFIG. 2, to maintain the sub-assembly of spacer, main gear, andwheel. The gear `18, vwheel V22, and spider 30 are all mounted on abushing 35 which is provided with a head which tits into an appropriaterecess in wheel 22, as shown, and the other end of which is peened overthe hub of gear 18, as indicated at 317. This bushing preferably has a`lrnurled outer surface to maintain alignment of the parts thereon. Thebushing is received on main shaft 20, and next to the toothed ratchetwheel 40, the latter being mounted upon an enlarged hub portion 42 ofthe main shaft. The main shaft also projects through a mounting frame orplate 45, and the end 46 of shaft 2@ is staked or deformed beyond orbehind the frame plate to maintain the sub-assembly in position.Similarly, the countershaft 1.5 is mounted in the frame plate 45, withthe gears 'i3 and 14tthereon. The ratchet wheel 40 includes a pluralityof driving dogs 5d which preferably are provided by deforming sectionsof the ratchet wheel to one side thereof as shown in FIG. 2, and theresultant drive dogs are engaged with the hub -52 of timer shaft 53,this shatft carrying one or more switch controlling cams 54 whichprovide the timer circuit control functions, as is well known in thatart.

The rotary drive from pinion 12 is transmitted to the main gear 13, `andthe planet rollers 25 are revolved accordingly. The rollers iengage witha drive cam arm 6i? during their course of travel around the main shaft20'. This arm is pivotally mounted at 62 and includes a hook portion 63at its outer end which is engaged with a spring 6ft, and the other endof this spring is anchored to a iixed point shown generally at `65. Thismay be, for example, a fixed point on the frame. The arm 60 carries adriving dog 7h including a tooth 72 which is engageable with any of theteeth on ratchet 'wheel 40. The dog 70' is in turn pivotally mounted at7 3 to arm 60, and th-us as the arm is swung counterclockwise (as viewedin FIG. 1) the tooth 72 will cam or drag over the ratchet wheel teeth,and as the arm swings in the opposite direction the driving dog willengage a tooth on the ratchet wheel and rotate it in a countercloclrwisedirection (as viewed in FIG. l).

in order to assure engagement of dog 7@ with the ratchet wheel, aso-called lock-in lever or pawl 75 is provided, mounted ifor pivotalmovement on a iixed stud 76. The lock-in pawl includes an arm portion 78extending in back of the tooth 72 on the driving dog 70 (IFIG. l) andassuring continuous contact between the driving dog and ratchet wheel4t?. The biasing action of Ipavvl 75 is obtained through a suitable hairspring 80 hooked around this pawl and anchored about stud 76. While thislock-in pawl construction is not essential to the present invention, itis :advantageous in promoting positive contact between the driving dogand the toothed ratchet wheel, and this feature is explained in greaterdetail in said United States Patent No. 2,916,923.

Another feature of theV lock-in pawl concerns its function as a stopforming a limit to the driving or descending motion of the arm 6d anddriving dog 72. This stop is formed by the shoulder -81 on lock-in piawl75. The driving dog '712 enga-ges this shoulder at the end of itsstroke, and at this time the lock-in pawl functions to maintain thedriving dog positively engaged with a tooth of the ratchet Wheel,requiring that substantial iforce be exerted to rotate the ratchet Wheelfurther in its driven direction. Thus, the lock-in pawl also functionsto promote a precise advance of the ratchet wheel, as explained in theaforementioned patent.

In order to prevent reverse or retrograde rotation of the ratchet wheel,for example as might be caused by the dog tooth 72 dragging over theratchet wheel during its rising or non-driving motion, a holding dog`82. is provided, having a tooth 83 engageable with any tooth on ratchetwheel 40, and pivotally mounted on stud 76. The dog $2 is urged intocontinuous contact fwith the ratchet wheel teeth by a hair spring 84which likewise may be anchored about stud '76.

The cam drive ann 60 is provided with a linear cam surface which isengaged by the planetary driving rollers 25. This cam surface may beconsidered as divided into three portions, as shown particularly in FG.4, these portions being an entrance and driving or raising ramp 9i?, adrive control ramp portion 92, an exit ramp portion 93.

For purposes of explanation, assuming that three planetary drive rollersare to be used as shown in 'FiG. 4, these rollers have been designated25a, 25h and 25C. They are in fact identical in construction, and eachper- -forms the same function in its sequence of rotation about the mainshaft 2i?. -In the assembly shown in FIG. 4, the arm 66* is shown in`full lines at the beginning of its ascending stroke, at which time thedrive roller 25a has just engaged the entrance or driving cam rampportion 90, while the roller 25h has passed otf the lend of the exitramp portion 93. The roller 25e is, of course, on the opposite side ofthe main shaft from arm 64)' and may be considered non-operative at thistime.

As the drive gear continues its forward rotation, which is nowconsidered to be counterclockwise in FIG. 4 (but corresponds toclockwise rotation of this gear as viewed in FIG. l) the roller 25awvill cause arm 60 to swing downward toward its dotted line position inFIG. 4, acting against the bias of spring 64. At this time the drivingdog 7i) is being raised or dragged across the teeth of ratchet wheel4i?, ywhile this Wheel is held stationary by the bolding dog 82. Thelock-in pawl 75 rfunctions at this time to maintain contact Ibetween thedriving dog and ratchet wheel 40.

When roller 25a leaves the raising or entrance ramp portion and passesbeyond the intersection thereof with the control ramp portion 92,`spring 6d- Will pulil arm 60 through its descending or driving stroke,and rroiler 25a -will pass over to the control ramp portion 92, as`shown particularly in FIG. 5. As this occurs, and arm 60 is descending,the driving dog 7? engages with la tooth on ratchet wheel 40, andcarries this wheel forward, producing an output rotation thereof(counterclockwise as viewed in FIG. 1), the angular extent of which isdetermined by the total :descending or driving movement of `arm 60.

in many prior yart devices the drive arm is at this time permitted todrop with an abrupt motion which inberently results` in rather largeacceleration and deceleration of the drive arm. However, in accordancewith the present invention the roller remains in contact with thecont-rol ramp portion 9'2 4and this maintains a control over the nate ofdescending or driving movement of arm 6b, resulting in a smooth drivingstroke which minimizes the tendency off driving dog 7 i) to throw theratchet wheel forward. It has been tfound that in some instances `suchthrowing action could lead to van angular movement o-f the ratchet wheelbeyond that of the predetermined motion of the driving dog. This actionhas actually been observed in some cases to cause `a significantuncontrolled advance rotation of the ratchet Wheel `and timer cams. Inany event, even if this throwing action might be `only to the extent ofone or two teeth passing under the driving dogs, such 'additional andunpredicted motion can result in an inaccurate cycle in the timer whichobviously produces unwanted results, whatever may be the apparatuscontrolled by the timer.

As the roller 25a advances beyond the control ramp portion 92, it willengage with the exit ramp section or portion 93, land thus maintain itscontact with the arm 60. Continued rotation of gear 18 and wheel 22 willcause roller 25a to move down the exit ramp portion 93 and the drivingor descending stroke of `arm 60 (and driving dog 72) is completed withthe driving dog 72. engaged against shoulder 81 ion the .flock-in pawl7'5. When the parts are in this position, and the next roller 25C hasnot as yet engaged the entrance ramp portion 90, the rollers will bemomentarily out of contact with the cam surface on the arm. It should benoted, however, that at no time latfter its engagement with entranceramp portion 90 does the active roller become momentarily `disengagedfrom the cam on the arm 60 until that active roller has completed itstraverse of the cam and moved beyond the exit ramp portion 93 when thestroke of arm 60 is completed as just described.

One significant advantage of this type of construction results from the`distribution of surfaces subject to wear. Thus, for example, each ofthe rollers 25 rotates within its bearing surfaces 28' on the gear 18and Wheel 22, respectively. This rotation occurs during traverse lof theroller in question over the cam surface on the drive lanm. Suchtraverse, however, is a rolling action rather than a sliding one, andthus there is very little if any wear due to friction on the peripheralsurfaces of rollers 25 which engage the cam on the drive arm, landlikewise of course there is little frictional wear on the respective camportions. IFurthermore, the pressure exerted by spring 64 through arm 60against the lrollers is transmitted to the bearing surfaces 28 which arein the form 'of journals, which are cylindrical iand of a width roughlyequivalent to the thickness of Igear 18 4and Wheel 22. There are aplurality of rollers, in a preferred construction according to theinvention, and thus the wear due to friction, which is a rolling bearingtype of wear, is distributed further. The result is an intermittentdrive construction which exhibits a substantially prolonged life incomparison to prior art devices.

The present invention also includes another novel feature which isparticularly clear from an inspection of FIGS. 1 and 6. As explainedabove, ratchet Wheel 40 drives the timer main or output shaft 53 whichrotates the timer control cams 54. In one embodiment of a timer, usedparticularly to control the cycling of an automatic dishwashing machine,the shaft S3 carries (in addition to other cams not illustrated) aterminal control cam 95 which maintains the contacts 160 closed duringone complete operating cycle of the ti-mer, and these contacts complet-ean energizing circuit through the timer motor 10, this .portion only ofsuch circuit being shown in lFIG. 6.

At the end of the cycle, the following contact drops into a niche 102 inthe surface of cam 95, and contacts 100 open to deenergize motor 10,stopping the timer yand terminating the cycle. In order to initiate anew cycle it is necessary to advance shaft 53, `and particularly cam 95,to close contacts d again. One convenient way of accomplishing thisfunction is by use of -a start cam- 165 also carried in iixed relationon shaft 53, `and presenting a starter surface 106 which can be engagedby la shaft or pin 105 which is depressed in the direction indicated bythe arrow, either manually or through some convenient mechanism, toengage surface y106 and advance the timer shaft `53 by an amountsufcient to close contacts y10i) and initiate a new cycle of operation.

During such starting of the timer the ratchet Wheel 40 is rotated in fanadvancing direction while the drive dog 72 and holding dog 83 remainstationary, the respective biasing forces on these dogs being resilientas previously described, and permitting such advancement of the timerparts relative to their driving mechanism. However, if driving dog 72 isseated against shoulder 81, and locked into the ratchet wheel, it hasbeen discovered that the force necessary to rotate shaft 53 lforstarting purposes is substantially increased over the force necessaryfor such purpose if the drive dog is maintained out of contact with ltheshoulder at this time. Accordingly, the cams 95 and 105 are so arrangedon slnaaft 53 that when the end of a cycle is reached, and the contacts100 part, that roller 25 which is then contacting the arm `6l) has justcompleted its traverse of the cam control portion 92, and rests upon theinitial part of the exit ramp portion 93. This condition is shown inFIG. 1. In such la position, the driving dog 72 is maintained slightlyaway from the shoulder 81 on the lock-in pawl, and starting rotation ofratchet 40 requires the lesser force previously mentioned.

While the form of apparatus herein described constitutes a preferredembodiment of the invention, itis to be understood that this inventionis not limited to this precise form of apparatus and that changes may bemade therein without departing from the scope of the invention which isdened in the appended claims.

What is claimed is:

1. A ratchet drive particularly adapted for positive ad. vancing of atimer mechanism, comprising a toothed ratchet wheel including `an`output drive thereon for intermittent rotary driving, means engagedwith said wheel and normally preventing rotation of said wheel in onedirection, a driving ydog engageable with the teeth on said wheel andmovable to rotate said wheel in the other direction through lapredetermined angular motion, a drive cam arm connected to said drivingdog, means mounting said arm for motion in a predetermined path withrespect to said wheel to move said driving dog along the teeth on saidWheel, a rotatable driving wheel and a plurality of drive rollersmounted thereon for independent free rotation while moving concurrentlywith said driving wheel to engage said larm and cause oscillating motionthereof, said arm having Ia cam surface engageble with said rollers andcontoured to be continuously in contact with said rollers in successionduring rising fand descending motion of said arm relative to saiddriving wheel producing driving motion of said driving dog lwithcontrolled acceleration and deceleration, means connected to rotate saiddriving wheel, and means maintaining contact between said cam surfaceand said rollers during relative movement therebetween.

2. Mechanism for producing intermittent rotary mo tion of predeterminedincrements, comprising a rotatable drive means, a drive wheel rotated bysaid drive means, at least one drive roller mounted on said wheel at apredetermined 'distance from the axis of rotation of said wheel, saidroller being freely rotatable on said Wheel, la drive cam arm pivotallymounted to extend in a plane intersecting the axis of said wheel andincludnig a cam surface thereon engageable with said roller, said camsurface including an entrance ramp portion, a control ramp portion, yandan exit ramp portion which are engaged in that succession with saidroller during :a single rotation of said wheel, means biasing said armtoward said wheel to maintain contact between said cam surface and saidroller during passage of said roller across said cam surface portions, aratchet wheel having an output drive thereon adapted :for intermittentrotary driving, means normally preventing rotation of said wheel in onedirection, and a driving dog carried by said arm and engageable withs-aid ratchet wheel to rotate said ratchet Wheel in the other directionthrough a predetermined angular motion related to the movement of saidfarm by interaction of said roller and said cam surface.

3. Mechanism for converting continuous rotary action into intermittentrotary motion of predetermined increments, comprising a continuouslyrotatable drive means, a drive wheel rotated by said drive means, aplurality of drive rollers mounted on said Wheel at la common distancefrom the taxis of rotation of said wheel, each of said rollers being`freely rotatable on said Wheel, a drive cam rarm pivotally mounted t-oextend in a plane intersecting the axis of said wheel and including acam surface thereon engageable with said rollers, said cam surfaceincluding an entrance ramp portion, a control ramp portion, and an exitramp portion which are engaged in that succession with each fof saidrollers during a single rotation of said wheel, means biasing said armtoward said wheel to maintain contact between said cam surface and saidrollers continuously during passage of said rollers across said camsurface portions, a ratchet wheel having lan output drive thereonadapted for intermittent rotary driving, means normally preventingrotation of said wheel in one direction, a driving dog carried by saidarm and engageable with said ratchet Wheel to rotate said' ratchet wheelin the other direction =by interaction of successive ones of saidrollers and ysaid cani surface, and a terminal control cam driven bysaid ratchet wheel fand controlling said drive means, said terminal cambeing related to said 5 arm 0am surface such lthat it stops said drivemeans with the tactve roller passing onto said exit ramp poriton.

4. A drive for a timer mechanism as `defined in claim 1. wherein saidmeans mounting said arm includes a pivotal mounting for said armproviding for swinging movement 10 thereof toward and away from the pathof said rollers.

ReEerences Cited in the le of this patent UNITED STATES PATENTS Clis'beeApr. 22, Wagner Sept. 4, Johanson Aug. 25, Finehout et a1. Jan. 13,Smith et al. Dec. 15, Schneider May 23,

1. A RATCHET DRIVE PARTICULARLY ADAPTED FOR POSITIVE ADVANCING OF ATIMER MECHANISM, COMPRISING A TOOTHED RATCHET WHEEL INCLUDING AN OUTPUTDRIVE THEREON FOR INTERMITTENT ROTARY DRIVING, MEANS ENGAGED WITH SAIDWHEEL AND NORMALLY PREVENTING ROTATION OF SAID WHEEL IN ONE DIRECTION, ADRIVING DOG ENGAGEABLE WITH THE TEETH ON SAID WHEEL AND MOVABLE TOROTATE SAID WHEEL IN THE OTHER DIRECTION THROUGH A PREDETERMINED ANGULARMOTION, A DRIVE CAM ARM CONNECTED TO SAID DRIVING DOG, MEANS MOUNTINGSAID ARM FOR MOTION IN A PREDETERMINED PATH WITH RESPECT TO SAID WHEELTO MOVE SAID DRIVING DOG ALONG THE TEETH ON SAID WHEEL, A ROTATABLEDRIVING WHEEL AND A PLURALITY OF DRIVE ROLLERS MOUNTED THEREON FORINDEPENDENT FREE ROTATION WHILE MOVING CONCURRENTLY WITH SAID DRIVINGWHEEL TO ENGAGE SAID ARM AND CAUSE OSCILLATING MOTION THEREOF, SAID ARMHAVING A CAM SURFACE ENGAGEBLE WITH SAID ROLLERS AND